Question

Which of the following has pH value of 10.5
A. Lemon juice
B. Milk
C. Softdrink
D. Lime water

Answer 1

Hint: Water-soluble compounds having a sour taste and turning litmus paper blue to red are called acids and they react with a base to form a salt. For Example: $HCl,HN{O_3},{H_2}S{O_4}$ etc.
Substances that give $O{H^ - }$ ions when dissolved in water are called bases. They turn litmus red to blue. For Example: Sodium Hydroxide, $NaOH$ , Calcium Hydroxide etc.$pH$ scale is a measure of the acidity or basicity of an aqueous solution. Acidic solutions (solutions with higher concentrations of ${H^ + }$ ions) are supposed to have lower pH values than basic or alkaline solutions. This scale is logarithmic. It inversely indicates the concentration of hydrogen ions in the solution.

Complete step by step answer:
Calculation of $pH$ :
To calculate the $pH$ of an aqueous solution, first of all we must calculate the concentration of the hydronium ion in moles per liter that is molarity. The $pH$ is then calculated using the equation:
$pH = - \log [{H_3}{O^ + }]$
Calculating
the Hydronium Ion Concentration from $pH$ :
The hydronium ion concentration can be found from the $pH$ by the following equation:
$
  [{H_3}{O^ + }] = {10^{ - pH}} \\
  or \\
  [{H_3}{O^ + }] = anti\log ( - pH) \\
 $
Calculating $pOH$
To calculate the $pOH$ of a solution, first of all we must know the concentration of the hydroxide ion in moles per liter that is molarity. The $pOH$ is then calculated using the equation given below:
$pOH = - \log [O{H^ - }]$
Calculating the Hydroxide Ion Concentration from $pOH$ :
The hydroxide ion concentration can be found from the $pOH$ by the following equation:
$
  [O{H^ - }] = {10^{ - pOH}} \\
  or \\
  [O{H^ - }] = anti\log ( - pOH) \\
 $
Relationship Between $pH$ and $pOH$ .
The $pH$ and $pOH$ of a water solution at ${25^0}C$ are related by the following equation.
$pH + pOH = 14$

Note:
$pH$ of lemon juice= $2$ i.e. acidic in nature
$pH$ of milk= $6.7 - 6.9$ i.e.acidic in nature
$pH$ of soft drink= $2.52$ i.e. acidic in nature
$pH$ of lime water= $12.4$ i.e. basic in nature
Limewater may be prepared by treating calcium hydroxide $Ca{(OH)_2}$ with water and then removing excess undissolved solute.